had been coring

• past perfect progressive

  past perfect progressive

  Used to describe an action that was ongoing continuously in the past up until another past event interrupted it.

  of core.
  core

  noun

  the central part of a fleshy fruit, containing the seeds.

Related Words

• basis
• body
• bottom line
• crux
• essence
• focus
• foundation
• heart
• importance
• nucleus
• origin
• root
• substance
• thrust